1.4 - enzymes

Question 1

what is the metabolic pathway an anabolic reaction?

Answer 1

building up molecules e.g. protein synthesis

Question 2

what is the metabolic pathway and catabolic reaction?

Answer 2

breaking molecules down e.g. digestion

Question 3

metabolic pathways are controlled by…?

Answer 3

enzymes

Question 4

the products of one enzyme-controlled reaction become..?

Answer 4

reactants in the next

Question 5

what properties do enzymes exceed?

Answer 5

• speed up reactions
• not used up
• they are not changed
• they catalyse many reactions per second

Question 6

how would you describe an enzyme?

Answer 6

a protein with a tertiary structure that form a globular shape with hydrophilic R groups on the outside.

Question 7

are enzymes soluble?

Answer 7

yes.

Question 8

what determines the bonds the amino acids make with each other in the protein - enzyme?

Answer 8

the elects in the R groups

Question 9

what holds the enzyme in its tertiary form?

Answer 9

hydrogen bonds, disulphide bonds and ionic bonds.

Question 10

what are the 3 sites called where the enzymes act?

Answer 10

• extracellular
• intracellular, in solution
• intracellular, membrane bound

Question 11

describe the lock and key theory.

Answer 11

unique shaped active site catalyses the one type of reaction

Question 12

define a enzyme - substrate complex.

Answer 12

a structure formed during an enzyme catalysed reaction where the the substrate and enzyme bind temporarily

Question 13

define activation energy.

Answer 13

the minimum energy that must be put into a chemical system for a reaction to occur.

Question 14

heat speeds up reactions in non-living systems however what would happen if you increased to the temperature to 40 degrees in living organisms?

Answer 14

cause irreversible damage to proteins and they denature

Question 15

what do enzymes do to the activation energy? what does this allow?

Answer 15

lowers it , reactions to occur at lower temperatures

Question 16

in a graph showing the formation of product overtime why does it plateau?

Answer 16

all the substrate has been used so no more product can be formed

Question 17

how does a change in temperature increase the rate of reaction?

Answer 17

INCREASED temperatures means more kinetic energise the enzyme and substrate collide more often.

Question 18

what happens if the temperature is increased to 40+ degrees?

Answer 18

increasing vibrations break the hydrogen bonds changing the structure of the enzyme meaning the substrate does no longer fit - enzyme denatures.

Question 19

what happens to the enzymes at very low temperatures?

Answer 19

inactivated although the shape is unchanged so if the temperatures were raised again they enzyme would work again.

Question 20

what can small pH do to the enzymes?

Answer 20

cause reversible changes and reduce activity

Question 21

what can a high pH do to a enzyme?

Answer 21

denature enzymes

Question 22

the rate of reaction increases as…?

Answer 22

the substrate concentration increases

Question 23

why is substrate concentration a limiting factor?

Answer 23

it controls the rate of reaction

Question 24

when all the active sites are full the enzyme is…?

Answer 24

saturated

Question 25

what does a inhibitor do?

Answer 25

combines with enzyme and prevents it forming an enzyme-substrate complex

Question 26

what is a competitive inhibitor?

Answer 26

have molecular shape complementary to active site and similar to substrate so they compete for active site

Question 27

a non-competitive inhibitor binds to an enzyme at an…?

Answer 27

allosteric site

Question 28

what is an examples of non-competitive inhibitors?

Answer 28

lead and arsenic

Question 29

as the inhibitor concentration increases the mass of product…?

Answer 29

decreases

Question 30

what are immobilised enzymes?

Answer 30

when they are bound to a inert matrix

Question 31

where are immobilised enzymes used?

Answer 31

industrial processes such as fermentation because they can be recovered for reuse

Question 32

name 4 advantages of immobilised enzymes.

Answer 32

• products not contaminated with enzyme
• enzymes are easily recovered for reuse
• enzymes an be easily added pr removed giving control over reaction
• incrases stability over a wider range of temp and pH then enzymes in free solution

Question 33

what drink can immobilised enzymes make? how?

Answer 33

lactose-free milk
milk is passed down column containing immobilised lactose. Lactase binds to active sites and is hydrolysed into components glucose and galactose.

Question 34

what else can immobilised enzymes be used for?

Answer 34

biosensors - tuen chemical signal into electrical